#include<REGX52.H>
#include"Delay.h"

unsigned char Key()
{
    unsigned char KeyNumber = 0;

    if(P3_1 == 0) {Delay(20); while(P3_1 == 0); Delay(20); KeyNumber = 1;}
    if(P3_0 == 0) {Delay(20); while(P3_0 == 0); Delay(20); KeyNumber = 2;}
    if(P3_2 == 0) {Delay(20); while(P3_2 == 0); Delay(20); KeyNumber = 3;}
    if(P3_3 == 0) {Delay(20); while(P3_3 == 0); Delay(20); KeyNumber = 4;}

    return KeyNumber;
}